I think it would be useful to begin a thread for returning Canadian travelers who are investigating options that involve flying to an American airport that is near the border (e.g. Buffalo), then
driving across. (See
this thread for those who want to
walk across and
this thread for those who want to
fly across.)
A number of car rental companies are allowing cars to be picked up at locations in the US and dropped at locations in Canada. There are also some limo services that will shuttle passengers across the border: (e.g.
Canam Limo (Buffalo area), as explained
here).
Please add other options and experiences that would benefit fellow travelers.